<!doctype html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>绝对定位</title>
	<style type="text/css">
		.box1{
			width: 100px;
			height: 100px;
			background: red;
		}
		.box2{
			width: 100px;
			height: 100px;
			background: blue;
			/*position: relative;*/
		}
		.son{
			width: 50px;
			height: 50px;
			background: yellow;
			position: absolute;
			top: 10px;
			left: 20px;
		}
		.box3{
			width: 100px;
			height: 100px;
			background: green;
		}
	</style>
</head>
<body>
	<div class="box1">1</div>
	<div class="box2">
		2
		<div class="son"></div>
	</div>
	<div class="box3">3</div>
</body>
</html>